To Thomas Henry Huxley   6th. Jan.¹

6th. Jan.

My dear Huxley,

I was puzzling my head for a name for that property and had asked Hooker to puzzle his, but your ‘frangi-flexibility’ comes nearer the thing than anything I had thought of. Still it does not quite please me, and for this reason. A flexible solid according to our hitherto notions must be elastic. Flexibility in a solid implies a power of regaining its shape when the strain upon it is removed. Our ice would not do so and therefore it is frangi-plastic rather than frangi-flexible; but you miss the alliteration in the former which to the ear is something. The particles of a plastic body move past each other and form new attachments as our ice does, but the particles of a flexible body move round each other. If you still consider the term applicable I am willing to let it go. Some term is necessary; and we should fix the theory by calling it the ‘frangi flexible theory.’ I had set down the ‘break and make’ theory; a better term than either would be one to include the idea of breaking with that of refreezing.² I had the account of our travels written much more fully at first but Francis thought it too full and I cut it down greatly. With regard to the arrangement I think it might be improved, but the change in this respect indicated by your heads would be a formidable one. You have only to remember that Stokes is to have the paper this week, and that I cannot lay a hand on it, except to insert half a dozen notes which are beside me ready written. I shall certainly when it comes into my hand cut away something about the tensions and pressures, so as to leave as little hold as possible upon this point. This I have set down among my notes. We must I think avoid diverting the mind too much from the real points at issue. In fact I have been thinking of omitting the whole of that about the Grindelwald glacier³ as really irrelevant, and if you encourage me in the least I will do so. Your little experimental devices are full of ingenuity but instead of expanding in this direction I have the strongest inclination to retrench. The arrangement is the point I think which the time at our disposal will confine us to. I am sure this can be made more effective and we might probably be permitted to do something at this even after the reading of the paper on the 15^th.⁴

Ever Yours | John Tyndall

In regard to the question ‘why does the glacier travel faster in wet weather.’ I ask in reply: does it travel faster? The observations upon which this conclusion rests appear to me to be next to worthless. But supposing it does, my temporary answer would be ‘that it is certain that sliding along the bottom [1 word illeg] hence to some extent.’ The theory of Saussure coexists to a certain extent with our theory; thus causing the motion to be made up of two true causes. Now the sliding will increase in wet warm weather and this would be an answer sufficient to deprive an objection founded on the faster movement in wet weather of all force. We cannot hope to solve every question at once, and to attempt now to examine the plasticity of ice is quite out of the question. Others have examined it—Parsons⁵ & Dolfuss⁶ for example—and found it more flexible, but I know what led them to think so, although I have made no mention of it. Indeed numberless things have occurred to me that I have not mentioned, simply because I wanted to present the subject as unencumbered as possible.

RI MS JT/1/TYP/9/2877

IC HP 8:25 (fragment)

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